Hello,
I am not at all an expert on guile-config, but I will help if I can.

Thank you to all who responded.

Usually if you have 64-bit libs in lib64, you have to pass --libdir
explicitly.

We've now concluded that that is, indeed, the answer to the
original question. The fallout question:
How much understanding of the machinery should be expected
of the hapless project builder?
Nelson has been doing this stuff for quite a while and has
reasonably good understanding of the process. From that
understanding, he made the assumption that a standard 64 bit
"Red Hat Enterprise Linux Server release 5.5 (Tikanga)"
installation would be compatible with installing Guile via
./configure&& make&& sudo make install
and not wind up with a frumitzed `guile-config link` output.
The assumption was incorrect and we now know that.